From: Sebastian Andrzej Siewior bigeasy@linutronix.de
commit 14132690860e4d06aa3e1c4d7d8e9866ba7756dd upstream.
Introduction of lockless subqueues broke the class statistics. Before the change stats were accumulated in `bstats' and `qstats' on the stack which was then copied to struct gnet_dump.
After the change the `bstats' and `qstats' are initialized to 0 and never updated, yet still fed to gnet_dump. The code updates the global qdisc->cpu_bstats and qdisc->cpu_qstats instead, clobbering them. Most likely a copy-paste error from the code in mqprio_dump().
__gnet_stats_copy_basic() and __gnet_stats_copy_queue() accumulate the values for per-CPU case but for global stats they overwrite the value, so only stats from the last loop iteration / tc end up in sch->[bq]stats.
Use the on-stack [bq]stats variables again and add the stats manually in the global case.
Fixes: ce679e8df7ed2 ("net: sched: add support for TCQ_F_NOLOCK subqueues to sch_mqprio") Cc: John Fastabend john.fastabend@gmail.com Signed-off-by: Sebastian Andrzej Siewior bigeasy@linutronix.de https://lore.kernel.org/all/20211007175000.2334713-2-bigeasy@linutronix.de/ Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sched/sch_mqprio.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-)
--- a/net/sched/sch_mqprio.c +++ b/net/sched/sch_mqprio.c @@ -531,22 +531,28 @@ static int mqprio_dump_class_stats(struc for (i = tc.offset; i < tc.offset + tc.count; i++) { struct netdev_queue *q = netdev_get_tx_queue(dev, i); struct Qdisc *qdisc = rtnl_dereference(q->qdisc); - struct gnet_stats_basic_cpu __percpu *cpu_bstats = NULL; - struct gnet_stats_queue __percpu *cpu_qstats = NULL;
spin_lock_bh(qdisc_lock(qdisc)); + if (qdisc_is_percpu_stats(qdisc)) { - cpu_bstats = qdisc->cpu_bstats; - cpu_qstats = qdisc->cpu_qstats; - } + qlen = qdisc_qlen_sum(qdisc);
- qlen = qdisc_qlen_sum(qdisc); - __gnet_stats_copy_basic(NULL, &sch->bstats, - cpu_bstats, &qdisc->bstats); - __gnet_stats_copy_queue(&sch->qstats, - cpu_qstats, - &qdisc->qstats, - qlen); + __gnet_stats_copy_basic(NULL, &bstats, + qdisc->cpu_bstats, + &qdisc->bstats); + __gnet_stats_copy_queue(&qstats, + qdisc->cpu_qstats, + &qdisc->qstats, + qlen); + } else { + qlen += qdisc->q.qlen; + bstats.bytes += qdisc->bstats.bytes; + bstats.packets += qdisc->bstats.packets; + qstats.backlog += qdisc->qstats.backlog; + qstats.drops += qdisc->qstats.drops; + qstats.requeues += qdisc->qstats.requeues; + qstats.overlimits += qdisc->qstats.overlimits; + } spin_unlock_bh(qdisc_lock(qdisc)); }